get $post in init filter or action?

It seems that $post is only available to hooks executing at certain times. I have an “init” hook that needs to pull some data from the database using the $post->ID.

So far my only workaround has been to add another filter on the_content, that uses $post to get the information I need. Unfortunately, it also echoes the return value to the screen, and fails to actually return it to the function that called the filter originally.

Here is the code that extracts the data I need, but echoes and fails to return the value:

add_filter('the_content', 'get_keyword');
function get_keyword()
{
    global $post;
    $keyword = get_post_meta( $post->ID, '_wpg_def_keyword', true );
    return $keyword;
}

Does anyone have any suggestion on how to get what I need and have it pass back to the calling function for later use in the plugin?

EDIT: To possibly make this more clear, I have a filter running at init, that needs to be able to retrieve information on the current post from the DB. To do this, it requires access to $post->ID. But that is not possible within init, so how can I get the result I need?

Thanks,

Jonathan

SOLVED:

Turns out the answer was simply to use url_to_postid like this:

$keyword = get_post_meta(
     url_to_postid( "http://".$_SERVER['SERVER_NAME'].$_SERVER['REQUEST_URI'] ),
     '_wpg_def_keyword',
     true
);

Works perfectly even from init.

Turns out the answer was simply to use url_to_postid like this:

$keyword = get_post_meta( url_to_postid( "http://".$_SERVER['SERVER_NAME'].$_SERVER['REQUEST_URI'] ), '_wpg_def_keyword', true );

Works perfectly even from init.